The root cause was the QuickLinkOptions object that is associated with the QuickLink population. This object was corrupted, causing an error when selecting a QuickLink as a user in that population.
Solution
IMPORTANT: Before executing this solution. Take a screenshot or notes on what quick links that the population has available and the configuration that they have in here.
Remove QuickLink population from the GUI.
Navigate to Gear Icon → Global Settings → QuickLink Populations
Delete population [Population Name] → [ 'X' Icon]
NOTE: Do not do to debug to do this. It won’t reach the QuickLinkPopulation object that needs to be removed.
Re-import QuickLink population from XML file (if in codebase) or re-create it in GUI
Reconfigure QuickLink options (adding viewable quick links, setting the For Self or For Others option).